The Impact Of Street Canyon On Traffic Noise And Noise Spreading Regularity Analysis

Traffic noise with its effect on building in street canyon is an important concern in environmental acoustics.Some problems need to be resolved,such as description of the noise distribution in street canyon with limited monitoring points,the establishment of model to predict the noise distribution,the discovery of the law of noise propagation,etc.An optimization model to improve arrangement of mersuring points has been established for description with least points.According to genetic algorithm,from the initial large number of mersuring points,the model searches optimizated points of the least number which is not much different with the former.To one special street canyon,the model has found the feasible measured arrangement with decreasing points number largely.Compared with initial points,the new points’ sound preasure level has changed in constraint conditions.A new compatation model for prediction of noise distribution in street canyon has been developed.The proposed model regards the traffic noise source as point source meaning a vehicle on the way.The different kinds of vehicles have their own sound level.According to ray tracing method,the model starts to trace the propagation pathes from every point source to one mersuring point and finds the sum.To do it again until getting the sound pressure of last measuring point.Compared with the existing models,the new model has not regarded the traffic noise source as line source and has used ray tracing method being more suitable for street canyon which increases computation difficulty but gets a better answer.The influence factors have been list including traffic noise source,street geometry and layout of the building.Besides,the law of both height and length direction noise propagation has been analysised.Changing the single factor,the simulation data has been obtained.The cubic curve has been selected during some common fitting curves to fit the former data.Based on the analysis of the whole fitting curves,the quantitative effect has been found.